Manufacture of isatin derivatives



Patented Dec. 14, 1937 UITED T 1;

ATENT OFFIQE MANUFACTURE OF ISATIN DERIVATIVES No Drawing. ApplicationApril 8, 1935, Serial No. 15,312. In Great Britain April 12, 1934 2Claims.

This invention relates to the manufacture of novel isatin derivatives.More particularly, this invention deals with N-alkyl-isatin-sulfopylchlorides, and a process of producing the same.

5 In my co-pending application, Serial No. 15,313 now Patent No.2,147,657, issued July 14, 1936, there is described the manufacture ofN-alkylcyano-formanilides. Another method is described in U. S. PatentNo.- 1,813,760 to Pfleger,

issued July 7, 1931.

According to the present invention I manufacture N-alkyl-isatin-sulfonylchlorides by treating' the said N-alkyl-cyano-formanilides withchlorosulfonic acid. The novel compounds are useful for the manufactureof dyestufis.

The following example in which parts are by weight illustrates but doesnot limit the invention.

Example 30 low leaves, M. P. 137139 C. Analysis confirms the empiricalformula corresponding to N-ethylisatin-sulfonyl chloride. The positionof I the sulfonyl chloride group has not been determined. Boiling withmethanol converts it into the methyl sulfonate which forms orangeplates, M. P. 131-l35 C. v

In a similar manner other N-alkyl-cyano- 5 formanilides, for instanceN-methyl-cyanoformanilide or N-propyl-cyano-formanilide or thosementioned in British Patent No. 306,450, may be converted into thecorresponding N-alkyl-isatinsulfonyl chlorides. Nuclear substitutionderival0 tives of these, for instance the halogen, alkyl or alkoxyderivatives, may likewise be ring closed to give the correspondingN-alkyl-isatin-sulfonylchlorides.

It will be understood that the process above de- 15 scribed issusceptible of wide variation and modification, without departing fromthe spirit of this invention.

I claim:

1. The process of producing N-ethyl-isatinsulfonyl-chloride whichcomprises stirring N- ethyl-cyano-formanilide with chlorosulfonic acidat about ordinary room temperature until reaction is substantiallycomplete.

2. N-ethyl-isatin-sulfonyl chloride, being when dry a greenish-yellowcrystalline compound having a melting point of 137-139 C. and beingidentical with the product obtainable by reactingN-ethyl-cyano-formanilide with chlorosulfonic acid at about ordinaryroom temperature until reaction is substantially complete.

' MAX WYLER.

i CERTIFICATE OF CORRECTION.

fatent No 2,102,10h. December 1A, 19 7. i mm mm 1 It is hereby certifiedthat err-or appears in the printed. specification loi the, abovenumbered patent requiring correction as 0 llows: First column, line 5,for the syllable "sulfopyl" read sulfonyl; line b, fer the patent hmnbe?"2,3 7,657" read 2,0)fl5657yand that the said. Letters Patent should beread with these corrections therein that the same may conform to therecord of the case in the Patent Office.

Signed. and sealed this 8th day of February, A. D, 1958 Henry VanArsdale, (Seal) 7 Acting Commissioner of Patents,

